Cleat Screw Problem
da borg
slightly and I need to loosen and re-tighten the hex screws in order to
correct the cleat, but one screw's hex seems to be stripped or rounded and
the hex wrench cannot turn it. I have tried several hex wrenches and they
all do the same thing. The screw fits flush with the cleat so I can't grab
it with anything else. Any advice on how to remove this screw?
Paul Southworth
The hex head in it is probably wrecked. It's a pretty small screw
for an ez-out, you could try hacking the cleat away with a hack
saw and then grabbing the screw with a plier. Or if you have a
tool for it (eg, Dremel) you could cut a slot across the screw head and
use a big flat-blade screwdriver to remove it - that's what
I would do myself.
Lack of lube on the screw threads, and using worn out allen wrenches,
are the most common reasons why cleat screws get wrecked.
A Muzi
news:u7fouak...@corp.supernews.com...
One crude but effective method is to slice it with a disc grinder (cutoff
blade) and use a screwdriver in the slot. Be brisk as too much heat is hard
on the cleat. Also the tool's vibration seems to actually help.
I have had good success on not-quite-so-rusty bolts grabbing the head with
an endcutter. Even ULS screws can be turned with a sharp one.
Grease the new bolts, BTW.
--
Andrew Muzi
http://www.yellowjersey.org
Open every day since 1 April 1971
Tom Kunich
these but they are a little hard to come by.
The easiest method is to use a Dremel tool with a cutoff disc. It only takes
half a minute to cut a perfect screw slot into the head. ALWAYS wear safety
glasses when you use a cutoff disc, they shatter quite often and can blind
you in an instant.
"A Muzi" <a...@yellowjersey.org> wrote in message
news:3c7803ae$0$98142$272e...@news.execpc.com...
Jim
Before you start getting wild go to Sears and buy the stripped screw
extractor kit. No drilling and it works really well on stripped phillips
screw heads.
Jim
Ryder Bayly
called an easy-out. It is similar in appearance to a drill bit. Get a size
small enough to go in and big enough to grab the edges. If you can't get
one to go in and grab, drill a small hole and insert an easy-out of the
appropriate size. You'll need a new screw.
"da borg" <dab...@yahoo.com> wrote in message
news:u7fouak...@corp.supernews.com...
Tom Paterson
>There is an inexpensive tool you can buy at Sears or most hardware stores
>called an easy-out. It is similar in appearance to a drill bit.
Well you might just be able to hacksaw a slot in the screw head if the cleat is
shot anyway, and the screw is a goner for sure. Try to leave a little of the
allen shoulder uncut if you can see in there. IOW, just saw cleat and all,
being careful to prevent collateral damage. Then get a screwdriver that fits
the slot, with a nice hefty handle, and crank it out. The ez-out is tricky,
drilling that hole straight, and a real skinny ez-out is ez-breakable. You
could find one that "fits" the allen hole about a third of the way up the
taper, and grind or cut it off there--jam it in and twist c-c. Cheaper than a
Dremel tool. The hacksaw dodge was standard practice when replacing Sidi cleats
of yore, and others. --Tom Paterson
Paul Kopit
with a lock jaw plier and turn it out.
On Sat, 23 Feb 2002 12:25:31 -0500, "da borg" <dab...@yahoo.com>
wrote:
Matthew Temple
Paul Southworth wrote:
<< snip >>
> The hex head in it is probably wrecked. It's a pretty small screw
> for an ez-out, you could try hacking the cleat away with a hack
> saw and then grabbing the screw with a plier. Or if you have a
> tool for it (eg, Dremel) you could cut a slot across the screw head and
> use a big flat-blade screwdriver to remove it - that's what
> I would do myself.
>
> Lack of lube on the screw threads, and using worn out allen wrenches,
> are the most common reasons why cleat screws get wrecked.
Just curious -- since making a flat-blade screw thread is the solution
to this problem, and I've now seen a rather large number of people
with exactly this problem, I've concluded that the cleat screws simply
have sockets that are too small and subject too easily to failure.
(Some bottle-cage-mounting-screws are bad, too.)
Though I agree that people ought to lube the threads and maintain
their allen wrenches (maintain == toss it out occasionally) I take
these too-frequent failures as a sign of bad design.
Matt Temple
--
=============================================================
Matthew Temple Tel: 617/632-2597
Director, Research Computing Fax: 617/632-4012
Dana-Farber Cancer Institute m...@research.dfci.harvard.edu
44 Binney Street, JF 314 http://research.dfci.harvard.edu
Boston, MA 02115 Choice is the Choice!
jobst....@stanfordalumni.org
>> I have SPD cleats on my shoes and recently, one of the cleats has
>> moved slightly and I need to loosen and re-tighten the hex screws
>> in order to correct the cleat, but one screw's hex seems to be
>> stripped or rounded and the hex wrench cannot turn it. I have
>> tried several hex wrenches and they all do the same thing. The
>> screw fits flush with the cleat so I can't grab it with anything
>> else. Any advice on how to remove this screw?
> Drill of the top of the screw. Remove the cleat. Hold the screw
> nub with a lock jaw plier and turn it out.
Have you done this? It is my experience that these are well hardened
screws and that, dirt removed, they seem almost stronger than the hex
key that turns them. I have always had them release with a sharp
snapping sound their conical heads with signs of rust. For this
reason, I always put plenty of grease on them when installing. I
don't think you can drill them out without a carbide drill and a vise
to hold the shoe in a drill press or milling machine.
An easy-out is also known as an easyin because the often beak off in
the screw they are to loosen. Thus it becomes a hard part in a softer
medium and is even more difficult t remove than the original screw.
Jobst Brandt <jobst....@stanfordalumni.org> Palo Alto CA
Tom Paterson
>Just curious -- since making a flat-blade screw thread is the solution
>to this problem, and I've now seen a rather large number of people
>with exactly this problem, I've concluded that the cleat screws simply
>have sockets that are too small and subject too easily to failure.
>(Some bottle-cage-mounting-screws are bad, too.)
>Though I agree that people ought to lube the threads and maintain
>their allen wrenches (maintain == toss it out occasionally) I take
>these too-frequent failures as a sign of bad design.
You "had" to make a screw slot in some old shoes because the allen head got
worn down from walking, along with the cleat.
Otherwise, proper wrench sizing (filling the allen socket) seems to be a
factor, as well as hardness. I had Craftsman allen keys that seemed a loose fit
back when. Replacements by unknown mfg.worked a lot better.
Perhaps someone has a source for better quality allen keys that will fit
tighter (plus hardness) and reduce problems. Snap-on? --Tom Paterson
Jim
Ease outs are brittle and will break off. They are also harder than the
screw and very difficult to drill.
The stripped screw removal tool I have from Sears requires no drilling.
Just put it against the stripped screw head and turn.
Instead of grease on the threads try anti-seize. It is used on auto
cylinder head bolts so the right torque value can be found w/o the
threads binding. It also makes removal easier.
Jim
Andy Chequer
All the other posters covered what I was going to say anyway, I just wanted
to ask wether or not anyone has tried putting plumber's tape (PTFE) on the
threads of the cleat bolts prior to installation? I'm going to try it next
time I need new cleats (I invariably use a 4 1/2" angle grinder to remove
the dead cleats - slowly so as not to melt the shoe - remove foot from shoe
before trying - I have never met anything that didnt yield to my trusty
DeWalt!)
It strikes me that PTFE tape has the advantage of not being washed away like
copper grease does, and one can do the bolt up tighter.
Any thoughts people?
Andy Chequer
Tom Paterson
Might not get "washed away" but doesn't really coat the threads like grease
does. At least with the tapered threads in most of plumberdom, taking apart a
taped joint will sometimes show gaps even with the tape massaged into the
threads before tightening. You could always put grease over the tape, like
using dope over tape.
I've greased cleat threads twice--run the greased screw in through the
engagement area, then pull it out, re-lube and tighten. Major effect might have
been to make me feel better about the situation, but there you go, "it seemed
to help".
--Tom Paterson
I
James Thomson
news:CC_d8.4059$hb6....@typhoon.sonic.net...
> Paul Kopit writes:
> > Drill of the top of the screw. Remove the cleat. Hold the screw
> > nub with a lock jaw plier and turn it out.
> Have you done this? It is my experience that these are well hardened
> screws and that, dirt removed, they seem almost stronger than the hex
> key that turns them. I have always had them release with a sharp
> snapping sound their conical heads with signs of rust. For this
> reason, I always put plenty of grease on them when installing. I
> don't think you can drill them out without a carbide drill and a vise
> to hold the shoe in a drill press or milling machine.
I've done a couple, using a hardened drill bit in a hand-held drill,
standing on the shoe to steady it. Both were Shimano SPD cleats. Each took
just a few seconds.
James Thomson
Paul Southworth
Matthew Temple <m...@research.dfci.harvard.edu> wrote:
>
>Just curious -- since making a flat-blade screw thread is the solution
>to this problem, and I've now seen a rather large number of people
>with exactly this problem, I've concluded that the cleat screws simply
>have sockets that are too small and subject too easily to failure.
>(Some bottle-cage-mounting-screws are bad, too.)
>Though I agree that people ought to lube the threads and maintain
>their allen wrenches (maintain == toss it out occasionally) I take
>these too-frequent failures as a sign of bad design.
Correct the design by going to a hardware store that has
a big fastener selection and buying replacement screws that
you can use a screw-driver on... Better yet, get them in stainless
and install them on day #1.
--Paul
Paul Beakley
wrote:
>I have SPD cleats on my shoes and recently, one of the cleats has moved
Had this happen to me, too, recently. Hammered a slightly larger torx
head into the bolt's stripped hole and it came out just fine. Torx is
good for the hammer method because the little edges cut nicely into
the bolt.
Good luck,
Paul
Outside America: Mountain Bike America -- Arizona
Guidebook available at bike shops, bookstores, and online
(480) 756-2460 | (602) 370-7107 cell
http://www.mountainbikearizona.com
Paul Kopit
motorcycles.
The lockjaw plier can really grab the nub and you have lots of
leverage. It also worked on changing out the top plate in SPD 747.
The part used to be available and used allen screws.
I use blue loctite on the cleat mounting hardware. Maybe it is better
than a rust connection for removal.
On Sun, 24 Feb 2002 05:12:02 GMT, jobst....@stanfordalumni.org
wrote:
Benjamin Weiner
> Otherwise, proper wrench sizing (filling the allen socket) seems to be a
> factor, as well as hardness. I had Craftsman allen keys that seemed a loose fit
> back when. Replacements by unknown mfg.worked a lot better.
> Perhaps someone has a source for better quality allen keys that will fit
> tighter (plus hardness) and reduce problems. Snap-on? --Tom Paterson
I use Bondhus, endorsed by observatories everywhere. Don't use
the ball end in anything really tight, it's only for getting at
screws with a constricted angle. IMO, the screw's hex socket
gets abraded and any tool becomes a slightly loose fit.
Look cleats come with flathead screws. However, the design
of the Look cleat allows a large pan screw head. For SPD cleats
you need a countersunk head. I rarely see metric countersunk
flathead screws, much less stainless, but no doubt you can get
them somewhere (McMaster-Carr if nowhere else, but you'll pay
for it).
The screws' M5x0.8 thread is actually very close to SAE 10-32,
a class B fit, but I don't like to make substitutions on
critical fasteners and cleat screws are in that category.
Ben
happy to see yet another fastener discussion
Matt O'Toole
"Tom Paterson" <dusto...@aol.comnospam> wrote in message
news:20020224003119...@mb-mh.aol.com...
> >Just curious -- since making a flat-blade screw thread is the solution
> >to this problem, and I've now seen a rather large number of people
> >with exactly this problem, I've concluded that the cleat screws simply
> >have sockets that are too small and subject too easily to failure.
> >(Some bottle-cage-mounting-screws are bad, too.)
> >Though I agree that people ought to lube the threads and maintain
> >their allen wrenches (maintain == toss it out occasionally) I take
> >these too-frequent failures as a sign of bad design.
I agree. They ought to use different bolts. I'm partial to stainless steel
square drives. The stainless ones are harder, and don't strip as easily.
They seem to take more torque than an allen or flat blade. It could be
argued that this is a non-standard too that we don't all have in our
saddlebags, but how often do these things need service in the field?
> Perhaps someone has a source for better quality allen keys that will fit
> tighter (plus hardness) and reduce problems. Snap-on? --Tom Paterson
You're assuming the bolt head is made to tight tolerances, but the allen key
is not. A dangerous assumption...
BTW, I've been riding with a worn cleat on my left shoe for over a year,
because I haven't gotten around to attacking the stripped, stuck bolt.
Matt O.
jobst....@stanfordalumni.org
> I've done a couple, using a hardened drill bit in a hand-held drill,
> standing on the shoe to steady it. Both were Shimano SPD
> cleats. Each took just a few seconds.
A few seconds to do what? What size hole did you bore and what did
you do after that?
jobst....@stanfordalumni.org
> Correct the design by going to a hardware store that has a big
> fastener selection and buying replacement screws that you can use a
> screw-driver on... Better yet, get them in stainless and install
> them on day #1.
I don't believe that you are better off with a screw driver,
considering the torque I have been able to exert on these screws.
This seems to me to be another case similar to people who strip the
extractor threads of their cranks. Done reasonably it isn't a
problem.
jobst....@stanfordalumni.org
> Yes, I've done this both with cleats and learned from working on
> rusty motorcycles.
> The lockjaw plier can really grab the nub and you have lots of
> leverage. It also worked on changing out the top plate in SPD 747.
> The part used to be available and used allen screws.
I suspect lockjaw pliers are what is called a vise-grip:
http://www.vise-griptool.com/index.asp
However, pliers do not have sharp jaw tips so they are not good at
grabbing barely protruding screws. In this case, the flat head screw
has no protruding "nub" to grab, they are flush screws so I don't
understand how you envision doing this. Besides, grabbing the sharp
edge of a flat head screw will not make a suitable point of
attachment. This sounds like and "if I were you" story from someone
who has never done it.
> I use blue loctite on the cleat mounting hardware. Maybe it is
> better than a rust connection for removal.
If you tighten the screw, blue Loctite won't prevent locking, the film
being displaced from the pressure faces and the rest (the uncured
portion) not preventing water intrusion.
James Thomson
news:ZUje8.215$mx4....@typhoon.sonic.net...
> James Thomson writes:
> > I've done a couple, using a hardened drill bit in a hand-held drill,
> > standing on the shoe to steady it. Both were Shimano SPD
> > cleats. Each took just a few seconds.
> A few seconds to do what?
A few seconds to drill the head off the bolt.
> What size hole did you bore
I forget whether it was a 5mm or a 6mm bit - probably the latter.
> and what did you do after that?
I fitted new cleats and went out riding.
James Thomson
Tom Paterson
>> Perhaps someone has a source for better quality allen keys that will fit
>> tighter (plus hardness) and reduce problems. Snap-on? --Tom Paterson
>
>You're assuming the bolt head is made to tight tolerances, but the allen key
>is not. A dangerous assumption...
>BTW, I've been riding with a worn cleat on my left shoe for over a year,
>because I haven't gotten around to >attacking the stripped, stuck bolt.
**Warning: Worn Cleats Might Be Hazardous To Your Health**
Clarifying: not an assumption, just exerience. No matter what brand, you need a
clean, tight, deep fit between tool and bolt head.
Also, have had experience with Vice Grips (end lock). Not to dispute those who
have had good results, but use the Liquid Wrench or whatever and try to get
that thread loose before you get to the "nub grabbing" phase. The next step is
repeated Vice Grip applications, resulting in twisting/breaking the splintering
bolt remainder down to the female threads. Have fun drilling out something that
small, round, hard, and nasty to advance the project further. That "torx" tip
dodge might be the best shot, post initial Allen key failure, so far. Vaya con
Dios, baby.
--Tom Paterson
Mark Hickey
I join Jobst in a state of confusion...
1) Start out with a cleat with only two bolts
2) Drill the head off one
:
:
5) Fit new cleat and go riding
Unless I'm missing something, you're missing something...
Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame
James Thomson
news:3c7a3f04...@netnews.att.net...
> I join Jobst in a state of confusion...
>
> 1) Start out with a cleat with only two bolts
> 2) Drill the head off one
> :
> :
> 5) Fit new cleat and go riding
>
> Unless I'm missing something, you're missing something...
What I'm missing is the desire to flesh out irrelevant details. But if you
insist ...
The cleat was indeed attached by two bolts. Only one could not be removed
by conventional means. I loosened the one that could, then drilled the head
off the second. I then removed the first bolt, gripped the stub of the
second with pliers, and holding the edges of the shoe plate between the
jaws of a large adjustable spanner, removed the stub of the bolt. I then
fitted new cleats to both shoes, having first removed the old cleat from
the second shoe by conventional means.
I believe I then took a bath, drank a glass of milk, watched 'Butch Cassidy
and the Sundance Kid' on television, and only then went out riding.
In fact I may have drunk the glass of milk before taking the bath - I'm not
sure. And my wife thinks it was 'High Noon', but I'm pretty certain it was
'Butch and Sundance'. If I'd been aware at the time that what I was doing
was impossible, I'd probably have taken notes.
James Thomson
Paul Kopit
heads are gone. Sometimes they have 2 sets of holes. If not, you
have a bigger nub to grab, maybe even something to put in a bench
vise. Otherwise, the inner plate is not that difficult to find.
On 25 Feb 2002 06:28:20 GMT, dusto...@aol.comnospam (Tom Paterson)
wrote:
Paul Kopit
Craftsman one is called.
On Mon, 25 Feb 2002 05:37:11 GMT, jobst....@stanfordalumni.org
wrote:
Alex Rodriguez
jobst....@stanfordalumni.org says...
>An easy-out is also known as an easyin because the often beak off in
>the screw they are to loosen. Thus it becomes a hard part in a softer
>medium and is even more difficult t remove than the original screw.
I wish I knew this yesterday when working on an exhause system. :)
--
-----------------
Alex __O
_-\<,_
(_)/ (_)
jobst....@stanfordalumni.org
>>>> I've done a couple, using a hardened drill bit in a hand-held
>>>> drill, standing on the shoe to steady it. Both were Shimano SPD
>>>> cleats. Each took just a few seconds.
>>> A few seconds to do what?
>>A few seconds to drill the head off the bolt.
>>> What size hole did you bore
>>I forget whether it was a 5mm or a 6mm bit - probably the latter.
>>> and what did you do after that?
>>I fitted new cleats and went out riding.
> I join Jobst in a state of confusion...
> 1) Start out with a cleat with only two bolts
> 2) Drill the head off one
> :
> :
> 5) Fit new cleat and go riding
> Unless I'm missing something, you're missing something...
This is the result of poor communication. From this I deduce that a
drill larger than the threaded portion of the flat head screw was used
to drill OFF the head of that screw. It should be noted that metric
flat head screws have an included conical angle of 90 degrees while
drills are 120 degrees. Therefore, this process would attack the
countersink in the cleat as well as the screw. Since a new cleat and
cleat paired washer will be used, this doesn't lose much.
The description given certainly leaves much out.
jobst....@stanfordalumni.org
> Clarifying: not an assumption, just exerience. No matter what
> brand, you need a clean, tight, deep fit between tool and bolt head.
You men full engagement.
> Also, have had experience with Vice Grips (end lock). Not to dispute
> those who have had good results, but use the Liquid Wrench or
> whatever and try to get that thread loose before you get to the "nub
> grabbing" phase.
That's a terrible vice not to use a vise for this. Get some tools man!
Tom Paterson
(I said)
>>No matter what
>> brand, you need a clean, tight, deep fit between tool and bolt head.
Jobst replied:
>You men full engagement.
"men"? Your glasses are on your head, Jobst. You can call it marriage if it
floats your boat.
>That's a terrible vice not to use a vise for >this. Get some tools man!
No stuck screws, but tools, I got. Books plumb full of wit, too. But thanks for
the offering.
Jobst--twice in one week, making with the ha-ha's--did you find out your
portfolio was 100% Enron-free? --Tom Paterson
Matt Temple
<< Snip >>
> I don't believe that you are better off with a screw driver,
> considering the torque I have been able to exert on these screws.
> This seems to me to be another case similar to people who strip the
> extractor threads of their cranks. Done reasonably it isn't a
> problem.
>
> Jobst Brandt <jobst....@stanfordalumni.org> Palo Alto CA
Jobst,
I have a number of brass woodworking screws that have a
square recess where the hexagonal allen head would go. If such a screw
existed in steel and you had the correct square-ended wrench, then
in theory, which of these sockets would allow the greater wrench torque
before failure. (Did that question make sense?)
Matt Temple
--
Matthew Temple
Bicycle Commuter
Director, Dana-Farber Cancer Institute Research Computing
Perfec...@research.dfci.harvard.edu "Choice is the Choice"
Matt Temple
Hey, my attribution disappeared, but I'll put it back: 8-)
-- Matt Temple <m...@research.dfci.harvard.edu> wrote:
<< snip >>
> > >their allen wrenches (maintain == toss it out occasionally) I take
> > >these too-frequent failures as a sign of bad design.
>
> I agree. They ought to use different bolts. I'm partial to stainless steel
> square drives. The stainless ones are harder, and don't strip as easily.
> They seem to take more torque than an allen or flat blade. It could be
> argued that this is a non-standard too that we don't all have in our
> saddlebags, but how often do these things need service in the field?
>
Can you get these square drive screws and screwdrivers easily? If so,
where? (I've only seen them for wood screws in brass)
jobst....@stanfordalumni.org
>> I don't believe that you are better off with a screw driver,
>> considering the torque I have been able to exert on these screws.
>> This seems to me to be another case similar to people who strip the
>> extractor threads of their cranks. Done reasonably it isn't a
>> problem.
> I have a number of brass woodworking screws that have a square
> recess where the hexagonal allen head would go. If such a screw
> existed in steel and you had the correct square-ended wrench, then
> in theory, which of these sockets would allow the greater wrench
> torque before failure.
First, I think it would be good to assume that hexagonal screw heads
and hexagonal sockets in screws have been developed over a long time
and are used widely in industry from toys to aircraft and space
vehicles. With the research and funds of these industries, coming up
with a square drive instead of a hexagonal one, ignores the design
constraints and function.
For a given screw size, a hexagon is 2.25 times torsionally rigid and
strong as a square inscribed in a given circle. That circle is the
screw head. Properly engaged internal hexagon screws allow for a
larger cross sectional area and one that is torsionally an optimum.
More than six yields too small a pressure angle and less than six too
weak torsionally.
There are other considerations in manufacture where screw heads are
cold formed including the hexagonal recess. Square corners are less
reliably formed and have greater stress concentrations.
You aren't going to invent a better mouse trap, now that many skilled
people have studied this problem. For small screws, the Torx drives
have an advantage, these things do not scale linearly.
http://www.camcar.textron.com/torxplus/
Edward Dike, III
Matt Temple <perfec...@research.dfci.harvard.edu> wrote in message
news:perfectlylost-6FF...@brnws01.ne.mediaone.net...
The square heads are called 'Robertson' heads, They are said to be the most
popular type of driver head in Canada, where they were developed in 1908.
They seem to be a good idea. They have been around a while, I don't know why
they haven't caught on more in the USA. I have only seen them in wood
fasteners.
http://www.rockler.com/ecom7/favorites.cfm?&DID=6&sku=2204&cs=1
ED3
jobst....@stanfordalumni.org
>>> I don't believe that you are better off with a screw driver,
>>> considering the torque I have been able to exert on these screws.
>>> This seems to me to be another case similar to people who strip the
>>> extractor threads of their cranks. Done reasonably it isn't a
>>> problem.
>> I have a number of brass woodworking screws that have a square
>> recess where the hexagonal allen head would go. If such a screw
>> existed in steel and you had the correct square-ended wrench, then
>> in theory, which of these sockets would allow the greater wrench
>> torque before failure. (Did that question make sense?)
> The square heads are called 'Robertson' heads, They are said to be
> the most popular type of driver head in Canada, where they were
> developed in 1908. They seem to be a good idea. They have been
> around a while, I don't know why they haven't caught on more in the
> USA. I have only seen them in wood fasteners.
http://www.rockler.com/ecom7/favorites.cfm?&DID=6&sku=2204&cs=1 ED3
I think that's mainly because torque is lower in wood than in metal
fastening. You'll also note that slotted screws are not used for high
torque applications.
Matt O'Toole
<jobst....@stanfordalumni.org> wrote in message
news:sGDe8.574$mx4....@typhoon.sonic.net...
> Matt Temple writes:
> >> I don't believe that you are better off with a screw driver,
> >> considering the torque I have been able to exert on these screws.
> >> This seems to me to be another case similar to people who strip the
> >> extractor threads of their cranks. Done reasonably it isn't a
> >> problem.
> > I have a number of brass woodworking screws that have a square
> > recess where the hexagonal allen head would go. If such a screw
> > existed in steel and you had the correct square-ended wrench, then
> > in theory, which of these sockets would allow the greater wrench
> > torque before failure.
> First, I think it would be good to assume that hexagonal screw heads
> and hexagonal sockets in screws have been developed over a long time
> and are used widely in industry from toys to aircraft and space
> vehicles. With the research and funds of these industries, coming up
> with a square drive instead of a hexagonal one, ignores the design
> constraints and function.
Those are all safe assumptions, but you still didn't answer Matt T's
question.
> For a given screw size, a hexagon is 2.25 times torsionally rigid and
> strong as a square inscribed in a given circle. That circle is the
> screw head. Properly engaged internal hexagon screws allow for a
> larger cross sectional area and one that is torsionally an optimum.
> More than six yields too small a pressure angle and less than six too
> weak torsionally.
Too weak torsionally for what, the wrench to break? The problem here is the
material of the bolt head yielding.
> There are other considerations in manufacture where screw heads are
> cold formed including the hexagonal recess. Square corners are less
> reliably formed and have greater stress concentrations.
That may be true, but again, it's not the issue here. Even if there's more
stress on the corners of a square, the bolt material has to squish further
for the hole to round out (compared to a hex). Plus, you lose less to the
corner radius with only 4 corners. This becomes more significant as the
bolt becomes smaller- the corners of the hole, and the driver, can only be
made so sharp.
> You aren't going to invent a better mouse trap, now that many skilled
> people have studied this problem. For small screws, the Torx drives
> have an advantage, these things do not scale linearly.
Indeed they do not scale linearly. For bolts and screws of this size, I'll
put my money on the Robertson (square) drive.
I spent the last three summers on a Canadian built sailboat. Most small
screws and bolts on this boat are Robertson drive. There are countless wood
screws going into teak, self tapping screws going into fiberglass, and small
machine bolts everywhere. A lot of them have corroded, been partially
stripped, etc. I've had plenty of opportunities to do side to side
comparisons of flat, Phillips, Robertson, and allen head screws. The
Robertsons win every time. Everyone else who picks up a screwdriver on this
boat says the same thing- "I wish this screw were one of those square hole
ones."
Robertson screws take more torque before they strip, are more forgiving of
having rust or dirt in the hole, and still work when partially stripped.
Of course, this is all anecdotal. But I'll bet you dinner that if you
actually tested this (for screws similar in size to a cleat screw), the
Robertson would come out ahead.
Torx don't count- I've never seen a countersunk Torx.
Robertsons will also stay on the end of a screwdriver better than anything
else.
If anyone wants Robertson drive bolts for their cleats, and you can wait
'till summer, let me know and I'll try to find some for you. I'm sure I'll
be groping through a Canadian marine hardware store at some point.
Matt O.
Matt O'Toole
> Can you get these square drive screws and screwdrivers easily?
Very.
> If so,
> where?
Canada.
Matt O.
James Thomson
news:rNxe8.440$mx4....@typhoon.sonic.net...
> This is the result of poor communication.
On whose part? It takes two to tango.
> From this I deduce that a drill larger than the threaded portion of the
> flat head screw was used to drill OFF
Is this one of those all-too-common cases of Anglo-American
misunderstanding? Should I have written 'off of'?
> the head of that screw. It should be noted that metric flat head screws
> have an included conical angle of 90 degrees while drills are 120
> degrees.
I've dug around in some boxes and produced a spare set of cleats and bolts.
These are SM-SH52 cleats, but the SH51 cleats that I removed by drilling
had the same form of attachment.
The conical part of the bolt head has a depth of only two millimetres. The
head then becomes a cylinder of diameter 6.4mm for about 1mm, after which
the conical profile is resumed. The total depth of the head, measured to
the base of the thread, is 4.0mm, and its diameter at its widest point is
9.7mm.
The slot in the cleat and the holes in the 'paired washer' are 8mm wide.
> Therefore, this process would attack the countersink in the cleat as well
> as the screw. Since a new cleat and cleat paired washer will be used,
> this doesn't lose much.
I probably eyeballed the new cleats and bolts before selecting a drill bit
with which to remove the stuck bolt. Looks like 6mm was a good choice.
> The description given certainly leaves much out.
The description left out nothing pertinent *that I could remember*. As I
said, if I had considered this a great exploit I might have paid more
attention, but at the time it seemed trivially simple. It still does.
James Thomson
Brian Huntley
>
> If anyone wants Robertson drive bolts for their cleats, and you can wait
> 'till summer, let me know and I'll try to find some for you. I'm sure I'll
> be groping through a Canadian marine hardware store at some point.
>
- what's the spec?
(I was buying a 1/4-20 stainless bolt for a camera mount and was
ticked that the had them ONLY in Robertson, as I don't have an R#2 in
my on-bike tool kit.)
Matt Temple
jobst....@stanfordalumni.org wrote:
Jobst, I'm not being cantankerous below, I'm actually asking
if I understand what you are saying. (I always have to translate
from "engineering" to my own internal version.)
> First, I think it would be good to assume that hexagonal screw heads
> and hexagonal sockets in screws have been developed over a long time
> and are used widely in industry from toys to aircraft and space
> vehicles. With the research and funds of these industries, coming up
> with a square drive instead of a hexagonal one, ignores the design
> constraints and function.
I'm not certain I understand your point of view on this here. Are you
saying that "These folks are wise and since they do it that way they
must be right"?
>
> For a given screw size, a hexagon is 2.25 times torsionally rigid and
> strong as a square inscribed in a given circle. That circle is the
> screw head.
Could the screw head itself actually deform then? When these
screws fail, as in when a cleat bolt can't be reomved, it's the
allen head wrench itself that's the culprit, no?
> Properly engaged internal hexagon screws allow for a
> larger cross sectional area and one that is torsionally an optimum.
> More than six yields too small a pressure angle and less than six too
> weak torsionally.
Drill bits, if not round, always have a square end though, don't
they. I'll guess that being held in a chuck tightly changes the
equation here.
>
> There are other considerations in manufacture where screw heads are
> cold formed including the hexagonal recess. Square corners are less
> reliably formed and have greater stress concentrations.
You think they'd be more likely to shear?
>
> You aren't going to invent a better mouse trap, now that many skilled
> people have studied this problem. For small screws, the Torx drives
> have an advantage, these things do not scale linearly.
Not inventing here. Trying to avoid a problem. I see, also that
the screws with the very-small sockets may be more a thing-of-the-past.
Dave Johnson
>I have SPD cleats on my shoes and recently, one of the cleats has moved
>slightly and I need to loosen and re-tighten the hex screws in order to
>correct the cleat, but one screw's hex seems to be stripped or rounded and
>the hex wrench cannot turn it. I have tried several hex wrenches and they
>all do the same thing. The screw fits flush with the cleat so I can't grab
>it with anything else. Any advice on how to remove this screw?
>
>
Sears makes a screw remover kit, sort of a cross between a reversed
drill bit and an easy-out. I've got a set, haven't had to use them
yet.
--
Sarcasm: The polite way of telling people what you really REALLY
think of them.
James Thomson
my ways: it seems that if I disagree with Jobst Brandt over even the most
trivial thing, every pedant in the camp is going to be on my back every
time I make an ambiguous statement. So I take it all back.
To the original poster - if you haven't shifted the bolt yet
notwithstanding all this advice, good and bad, I've prepared some ascii
art - a USEnet first for me:
_____ _____
\ | | /
\ | | /
| |_____| |
\ /
| |
| |
| |
| |
| |
|_____|
You need to view this in an evenly spaced font for it to make sense. This
is the bolt in profile, with a 4mm socket in the head. I gave the
dimensions previously. First, go to your local bike shop and ask them for a
replacement bolt. Next, if you're comfortable with this sort of thing, take
the hardest 6mm drill bit in your collection, and steadying the shoe
somehow (I stood on mine and drilled straight down towards the floor) drill
into the socket head. Wear eye protection. You can see that there isn't
much material to remove, and the drill won't contact the cleat itself. The
head should pop off the bolt in a few seconds.
HTH
James Thomson
Robert Perkins
cleat, taking the bolt head with it. My nephew had borrowed a pair of my shoes
and had stripped the hex bolt trying to change the cleats. Downside- you have
to buy a new cleat.
Rob
da borg wrote:
> I have SPD cleats on my shoes and recently, one of the cleats has moved
> slightly and I need to loosen and re-tighten the hex screws in order to
> correct the cleat, but one screw's hex seems to be stripped or rounded and
> the hex wrench cannot turn it. I have tried several hex wrenches and they
> all do the same thing. The screw fits flush with the cleat so I can't grab
> it with anything else. Any advice on how to remove this screw?
--
Robert Perkins
Program Manager
Caspian Networks
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